JPH0767512B2 - Presser foot lifting assist device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a presser foot lifting assist device for sewing machines.

2. Description of the Related Art A presser foot lifting device of a sewing machine is used for moving cloth before and after or during a sewing operation, or for performing pleated sewing, and is usually a foot pedal or JP-A-51-74745. It is operated by a solenoid or other power means as shown in JP-A-51-74746 and WO085 / 04430.

The presser foot of the sewing machine is normally pressed against the feed dog by a strong spring in order to securely clamp the cloth in cooperation with the feed dog to give a feed action, and the presser foot is frequently raised against the pressing force. In the garment factory where this is done, a great deal of labor is required to perform this with a foot pedal, and there is a problem that a large amount of electric power is required when this is done by a power means such as a solenoid. Further, in the sewing machine which also uses the upper feed dog, a larger force is required to raise the upper feed dog at the same time as pressing.

The height to which the presser foot is raised differs depending on the type, shape, and thickness of the cloth to be sewn, and the work content. For example, a thin small cloth piece may be moved or pleated sewing work. In this case, only the presser foot needs to be slightly lifted, and the presser foot needs to be elevated to move a stepped cloth or a large intricately sewn cloth. However, as described above, the presser foot is normally pressed by the spring, and if the presser foot is pushed up against this, the force must be increased almost in proportion to the ascending distance. In order to keep it at a much higher position, the load on the foot is large for the foot pedal type, and when using power means, it is necessary to have the ability to support it at the highest position, and always use a strong one. I was preparing.

Therefore, in the present invention, in the initial stage of raising the presser foot, the force is raised with a small force, and with a certain height or more, the force is raised with a large force, so that human power or power is used without waste and rationalization of sewing work and equipment is achieved. Is to measure.

Means for Solving the Problems That is, the present invention is to support the presser foot that is supported on the needle plate of the sewing machine and is pressed downward by the spring, and the presser foot to the spring pressure by the main drive source such as a foot pedal or a solenoid. A presser foot lifting device for a sewing machine including a driving body that moves so as to move upside down is provided with an auxiliary drive source that operates in association with the movement of the driving body and increases its lifting force. This auxiliary drive source is, for example, one in which a pair of magnets are arranged opposite to each other on the side of the driving body and on the side of the fixed portion of the sewing machine in the movement path of the driving body. In this case, as a result of the movement of the driving body, the magnets approach each other, and as a result, the attractive force increases and the ascending force can be increased, and the ascending position can be maintained.

Further, the auxiliary drive source may be arranged such that a position detecting portion of the drive body is installed on the moving path of the drive body and the auxiliary drive source is operated based on the detection. A main drive source is required to drive the drive body first. As the drive source, a human power means such as a foot pedal is used,
Use a solenoid, motor, air cylinder, or other power means that is activated by a switch that is operated with your hands, feet, or knees so that the auxiliary drive source can continue to operate after activation, or the pressurization force can be reduced slightly. When lowering the foot, for example, the force of the main drive source may be weakened to move the presser foot downward, and the action of the auxiliary drive source may be canceled along with the movement. In addition, one of the pair of magnets may be a magnet and the other may be replaced with a magnetic material such as soft iron. Further, a weight may be used as an auxiliary drive source, and the center of gravity of the weight may be moved by the movement of the driving body so as to have the effect of raising the presser foot.

Action When using the above-mentioned solution, first, the main drive source that raises the presser foot such as a foot pedal or power drive source to a predetermined height does not require a large force because the spring pressing force is relatively small. That is, the presser foot can be raised with a small driving force at first.

Then, when the position of the presser foot becomes higher and the pressing force of the spring increases, and when a large force to counter this is required, the auxiliary drive source acts, so that the presser foot can be raised even higher.

In this case, when a pair of magnets are arranged opposite to each other on the driving body side and the fixed portion side of the sewing machine in the moving path of the driving body, the magnets approach each other as the driving body moves, and the attractive force is increased.
Moreover, the activation means such as a switch can be omitted.

Embodiment An embodiment of the present invention will be described with reference to FIGS. 1 and 2. That is, FIG. 1 shows an overlock sewing machine having an upper feed dog 1, in which a presser foot 2 and an upper feed dog 1 which swings back and forth and up and down are pressed downward by springs 4 and 5, and a groove of a needle plate 6 is shown. The cloth (not shown), which is arranged to face the lower feed dog 8 which swings back and forth and up and down through 7 and is fed onto the needle plate 6, is sandwiched by these three members, and the vertical feed dog is rocked back and forth. It is designed to feed the cloth by movement. Also, although not shown in the figure, the lower feed dog is divided into front and rear parts so that they can be differentially moved back and forth, and it is possible to carry out shirring stitches and pleated stitches. The presser foot 2 and the upper feed dog 1 are lifted by a presser lifting device 9 similar to the one in Japanese Utility Model Laid-Open No. 60-63174 to release the clamp of the cloth. It is equipped with a fixed presser foot lifting arm, an upper feed bar lifting arm 12, a presser foot lifting drive arm 13, a link 14, and a presser foot lifting lever 15, which are fixed to the sewing machine frame 16 with a step screw 17. A spring 18 that is movably supported and that biases the presser foot lifting arm in a counterclockwise direction so that the presser foot arm does not always act on the presser foot 2 and the presser foot main drive source and auxiliary drive source. And a chain 19 for connecting. In the figure, reference numeral 20 denotes a magnet unit as an auxiliary drive source, which is fixed to the sewing machine table 21, and inside the frame 22 made of aluminum, a moving magnet M1 and a fixed magnet M2 are installed as shown in FIG. The moving magnet M1 is fixed to an intermediate portion of a vertical movement shaft 23 that vertically penetrates the frame body 22, and the upper end of the vertical movement shaft 23 has a chain 19
Is connected to the presser foot lifting lever 15 via the
Is connected to the foot pedal 24 through. Further, the fixed magnet M2 is provided with a hole 25 in the center thereof and is fixed to the upper end of a cylindrical magnet support 26 having a hole for penetrating the vertical motion shaft 23 and also penetrating the vertical motion shaft 23. The body is provided with a screw 27 on the outer periphery, and a screw hole 28 provided at the bottom of the frame body 22.
It is fitted with a height adjustable and is fixed by a nut 29.
The magnets M1 and M2 are housed in stainless steel dish-shaped frames 30 and 31 to prevent the magnetic field lines from diffusing.
Spacer that regulates mutual magnetic force spacing when M1 is suction-pressed
32 are arranged. In this embodiment, the lifting height of the engaging portion 33 with the chain 19 of the presser foot lifting lever 15 is 17 mm, and when the engaging portion 33 is pulled downward with a force of 3.6 kg, it descends by about 9 mm and the presser foot 2 Rises, and when further force is applied, the upper feed dog 1 rises with the lowering of the engaging portion 33, and to move the entire lift 6.
Requires 6 kg of power. On the other hand, the magnets M1 and M2 of the magnet unit
The mutual suction force of the changes according to the interval, and the interval is 1.0m
Use 2.4kg weight for m, 3.6kg weight for 0.5mm, 7.0kg weight for close contact.
When 3 is lowered, M1 approaches magnet M2, and when it is lowered 10 mm, the distance becomes 1 mm, and 0.5 mm
A thick spacer 32 is interposed between the spacers 32 to limit an increase in suction force so as not to become an obstacle when lowering the presser foot 2.

With the above-mentioned structure, when the foot 2 is slightly raised, it can be lifted by operating the foot pedal in the same way as the conventional one, and if the stepping amount is 10 mm, the magnet M
The distance between 1, M2 is 1.0 mm, and the suction force of 2.4 kg can work to raise the presser foot 2 high, that is, as a force of stepping down by 10 mm, only a stepping force of 4.6 kg is required in this embodiment. Once the magnets M1 and M2 are crimped at the interval of 0.5 mm, a force of 3.6 kg is applied, and even if the upper feed dog 1 is raised, it is not necessary to put more force on the foot. In addition, since the magnets M1 and M2 are used in this embodiment, the presser foot is kept for a long time, and even if the presser foot is repeatedly moved up and down, it does not generate heat, consumes no electric power, and has a weak stepping force. It only costs. When the force of stepping on the foot pedal 24 is reduced, the force generated by the springs 4, 5 and 18 is applied to the magnets M1 and M2.
Since it is larger than the force due to, the presser foot 2 and the upper feed dog 1
Descends.

Effects As described above, since the present invention includes the auxiliary drive source having the magnet that operates in association with the movement of the drive body that moves to raise the presser foot, the main drive source does not require a large force,
In addition, the auxiliary drive source will operate only when necessary, and the work and equipment can be rationalized. Further, since the attraction force changes due to the change in the mutual distance between the magnets, the switches can be omitted, and the maintenance cost is hardly required.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of the present invention, and FIG. 2 is a partial sectional view. 2: Presser foot, 4,5, 18: Spring, 15: Presser foot lifting lever, 20: Magnet unit, 24: Foot pedal, M1: Moving magnet, M2: Fixed magnet

Claims (1)

[Claims] 1. A presser foot which is supported on a needle plate of a sewing machine and is pressed downward by a spring, and a drive body which is moved by a main drive source so as to raise the presser foot against spring pressure. In a sewing machine including a presser foot and an auxiliary presser foot drive source that operates in association with the movement of the drive body, a pair of magnetic bodies, at least one of which is a magnet, is fixed to the drive body and the sewing machine as an auxiliary drive source. The magnetic parts are arranged so that they face each other, and when the driver is moved so that the presser foot rises, the distance between the magnetic members approaches and the force of the driver increases due to the magnetic force. A presser foot lifting assist device for sewing machines, characterized in that